Conventionally, a two-stage pressurizing refrigeration cycle is known to be capable of performing a two-stage compression operation and a single-stage compression operation (see, for example, Patent Document 1). In the two-stage compression operation, both of the two compressors are operated. In the single-stage compression operation, one of the two compressors is operated.
In the technique described in Patent Document 1, the refrigeration cycle can selectively perform the two-stage compression operation or the single-stage compression operation, thereby exhibiting its capacity corresponding to a load on the refrigeration cycle to improve the operation efficiency of the entire cycle.